The detection of volatile organic compounds (VOCs) is of potential importance in many applications due to environmental and safety concerns. Various methods for VOCs detection have been developed using photoionization, gravimetry, spectroscopy, and so forth. In many current commercialized VOCs detection technologies, VOCs cannot be identified. For example, the popular detection technology, Photo-Ionization Detection (PID), requires prior identification of any VOCs in order to obtain quantitative information. In order to identify VOCs, sophisticated and expensive equipment such as, for example, Gas Chromatography-Mass Spectrometry (GCMS) equipment is generally used. Despite miniaturization efforts, GCMS remains difficult and expensive to use in the field (e.g., in a manufacturing facility or shop).
Various absorptive capacitance sensors or optochemical sensors have been devised that include a dielectric microporous material sandwiched between two layers, at least one of which is porous to analyte vapors (e.g., volatile organic compounds) that become absorbed by the dielectric microporous material. As used herein the term “absorbed” refers to material becoming disposed within the dielectric microporous material, regardless of whether it is merely adsorbed to the pore walls, or dissolved into the bulk dielectric microporous material. These sensors detect changes in properties of the microporous material due to absorbed VOCS. For example, optochemical sensors detect spectral changes in reflected light caused by a change in the index of refraction of the dielectric microporous material, and capacitance sensors detect changes in capacitance caused by a change in dielectric constant of the dielectric microporous material.